VSV Vaccine Early Immune Response Findings May Help Rapid Countermeasure Development

Ebola virus (green) on a cell in culture. The virus was isolated in November 2014 from patient blood samples obtained in Mali. Credit: NIAID.

Recombinant vesicular stomatitis virus–Zaire Ebola virus (rVSV-ZEBOV) is one of the most promising candidates against the Ebola virus. In phase I of the clinical trial in 2016, it proved to be a safe and effective vaccine and is expected to be approved this year by the U.S. Food and Drug Administration.

Researchers at the Heinrich Pette Institute and the University Medical Centre Hamburg-Eppendorf (UKE) this week published a study on early responses of the innate immune system in humans who have been vaccinated with vesicular stomatitis virus (VSV), which when weakened and genetically modified, expresses a glycoprotein of the Ebola virus.

For the study, blood samples were analyzed for changes in cytokine levels, innate immune cell subsets, and gene expression. The team identified a signature of five early immune markers correlating with the indicative antibody titer four weeks after vaccination. Among these biomarkers was IP-10 (interferon-gamma induced protein 10). The identification of IP-10 marks the first time a soluble immune marker could successfully be identified as “activated” shortly after vaccination, and correlates with the degree of subsequent antibody response regardless of other early immune markers.

The finding could assist future efforts to increase the efficacy of the VSV vaccine for Ebola or other emerging viruses (such as Zika) by manipulating IP-10.

The development of rVSV-ZEBOV was supported by the WHO-led VEBCON. The German Centre for Infection Research supported the preparation of the studies at the UKE in Hamburg and in Gabon and provided the initial funding, the Federal Ministry of Health (BMG) and the British Wellcome Trust provided the funds to prepare and conduct the clinical trial. The Canadian health authorities donated the vaccine candidate to the WHO, which then made it available for these trials.